WO1990005035A1 - Ensemble filtre a support integre - Google Patents

Ensemble filtre a support integre Download PDF

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Publication number
WO1990005035A1
WO1990005035A1 PCT/US1988/004038 US8804038W WO9005035A1 WO 1990005035 A1 WO1990005035 A1 WO 1990005035A1 US 8804038 W US8804038 W US 8804038W WO 9005035 A1 WO9005035 A1 WO 9005035A1
Authority
WO
WIPO (PCT)
Prior art keywords
assembly
screen
filter
felt
bonded
Prior art date
Application number
PCT/US1988/004038
Other languages
English (en)
Inventor
John H. Lutz
James L. Manniso
Craig R. Rinschler
Gordon R. S. Smith
Original Assignee
W. L. Gore & Associates
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by W. L. Gore & Associates filed Critical W. L. Gore & Associates
Priority to PCT/US1988/004038 priority Critical patent/WO1990005035A1/fr
Publication of WO1990005035A1 publication Critical patent/WO1990005035A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/39—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type

Definitions

  • a filter known in the art as a filter leaf assembly.
  • a filter known in the art as a filter leaf assembly.
  • one drops one or more large, usually rectangular, filter frames covered by a filter cloth or bag into the tank, draws a vacuum within the filter bag to draw the liquid to be filtered inside the bag, and pumps the liquid out of the bag.
  • Each filter frame is lifted out of the tank periodically when it has become so loaded with solids as to reduce the filtration rate to an ineffective or uneconomic extent, and the solids are then knocked off by vibration, scraping, washing, shaking or concentrated in the filter apparatus, and the filter cycle repeated.
  • the filter bag used over the frame is usually a woven filter cloth, sewn at intervals into pockets which contain long molded plastic or metal stays or shapes inserted into the pockets to hold the cloth apart, to resist pressure, and to stiffen the bag.
  • the stays are as long as the filter cloth, molded into a shape which has channels or grooves for the liquid being.fiItered to flow within, and at the same time molded into a shape which is inherently strong enough to resist the pressure on the outside of the filter when it is nearly clogged by a thick cake of solids.
  • the support frame is usually rectangular, supports the pocketed envelope shaped filter cloth, the drain channel stays or shapes, and a filtrate receiver collector which may be a wood, metal, or plastic header or manifold.
  • the top of the filter cloth is gathered and sealed for a vacuum-tight closure to the filter assembly on this header or manifold.
  • a typical example of this type of filter is a Diastar tradenamed filter apparatus developed by Filters Gaudrin (France). Also known are Moore filters, of similar construction, which have been used in gold mining and the sulfate process for titanium dioxide. All the presently known filter leaf assemblies, where reversed flow is used, have in common a number of problems.
  • the filter cloth has to be sewn to form pockets to hold drain inserts which prevent the filter cloth from collapsing under pressure. The drain inserts themselves block off some of the flow of filtrate.. Needle holes from sewing must be sealed to prevent filtrate leakage. This can be expensive and time consuming. Since many pockets are needed to provide adequate drainage, sewing itself becomes expensive.
  • standard filter media such as felts and cloths tend to clog with solids which penetrate into the interstices -to cause high operating pressures and reduced through-put.
  • ridged and corregated plates sometimes manufactured from nets of expanded metal sheets, which can be inserted ' into filter bags for similar filtration as disclosed by Roos, et al, in U.S. 4,256,586.
  • corregated filter media such as the filter panels of Bourdale. as shown in U.S. 3,358,843 and U.S. 3,279,616, which are useful in filter cartridges.
  • Corregated plates have been used between filter elements in stacked annular filter arrangements, such as those provided by Gutkowski in U.S. 3,209,915.
  • the principal object of the present invention is to provide a singularly light-weight and efficient substitute or replacement for heavy canvas or cloth filters which do not filter particularly well, clog easily during the filtering cycle, and sometimes present expansion problems or bag outwardly during the cleaning cycle.
  • the present invention provides an integral light-weight and efficient filter medium by bonding, preferably by heat, a thermoplastic screen of mesh size about 1/4" to 5/8" square which has been bent into a regular repeating angled or sine-curved shape, to the thermoplastic-organic polymer felt sides of two sheets of composite microporous organic polymeric membrane/thermoplastic organic polymeric textile felt.
  • the filter media composites bonded to the screen give an integral corregated structure of relatively great compression strength, which can resist easily the pressures developed during the filtration cycle and subsequent backpulse cycle if used. Sewing is not utilized to form either the filter envelope or filter drain pockets.
  • the microporous membranes provide leakproof, efficient filtration by means of low pressure drop, high product through-put, near-complete filter cake release, high filtrate clarity, and prolonged filter life and can be selected from materials, such as polytetrafluoroethylene, which can be cleaned easily during the wash cycle, as the filter cake will not adhere to them very well.
  • the bonded integral filter leaf filter of this invention eliminates most of the problems associated with filter leak filters in the past, in particular those associated with, media clogging and sewn construction.
  • Fig. 1 is a perspective view of the filter leaf assembly, open at the top to reveal the undulating screen separator and lower cut-away portions to the interior near the bottom of the screen. A cut-away portion of the header or manifold to which the screen and filter cloth portions are attached is also given.
  • Fig. 2 is a cross-section of a segment of the screen through a side member and bottom member of the support frame and through the polymeric membrane filter cloth composite and edge seal.
  • Fig. 3 depicts a segment of an example of the bonded integral filter.
  • Fig. 4 shows a segment of a lateral cross-section through the filter leaf assembly.
  • Fig. 5 and Fig. 6 describe alternate forms of thermoplastic polymer screen for use as core screening material in the assembly.
  • FIG. 1 is the integral filter leaf cloth assembly of the invention as shown in Fig. 1. Flaps 2 of the composite filter cloth used in the invention are drawn aside or bent back so as to reveal the interior of the assembly, which consists of the frame 5 and the screen 3_. In Fig. 1 the top of the two side members of the frame are revealed and the bottom member.
  • the top bar or frame member is a header 10 or manifold IfJ formed from several pieces of metal, wood, or plastic which fit together to form a bar which is shaped and arranged to hold in place the ends of the side members 5 of the frame.
  • the top portion of the filter cloth is clamped or held in place about the header 10 my means for effecting a liquid and/or gas-tight seal between the filter cloth and the header/manifold 10.
  • Lifting lugs IL are fitted to the side member 5 of the frame to provide a means for removing a frame from a tank of material to be filtered.
  • a vaccum port 12 is set into mainfold 10 to provide access to the interior for drawing off filtrate under vacuum and slot H is provided to accommodate passage of lifting lug H.
  • the undulating thermoplastic polymer screen 3 holds apart the two layers of filter cloth and is bonded, preferably by heat sealing, at the apex of each fold to the filter cloth.
  • the filter cloth 2 is faced felt side to the screen and bonded felt to screen.
  • a heat-sealed side seam 4 is also made of each side of the assembly, felt-to-felt to provide a strong liquid- and gas-sealed seam of considerable mechanical strength.
  • the side members 5 of the frame may be pipe or tubing of metal or possibly plastic materials resistant to pressure and corrosion by the materials being filtered, and strong and stiff enough to form a frame of adequate strength for the loads being carried on the filter frame. They may also be solid and may be also entirely absent in some cases where no great strength is required for lifting heavy loads by means of the frame.
  • the side bars 5 attached to a bottom member which is of similar materials, shaped to hold the ends of the side bars 5.
  • Bottom bar £ shows through cut-away section of the filter cloth.
  • Figure 2 shows a cross-section of the end of a frame side bar 5_ heat sealed 4 inside two layers of filter cloth.
  • Bar 5_ is screw-threaded into frame bottom bar 2 at its end .
  • the filter cloth composite layers of microporous organic polymeric membrane £ and organic polymeric textile felt 7 shown in proper relation to the frame bars and the seal 4 effected by heat felt layer to felt layer.
  • Bars 5 and 9 are not always hollow and may be entirely absent or not always needed.
  • Figure 3 describes a section of the integral bonded filter leaf assembly of the invention, where the undulating thermoplastic screening 3 material and the filter cloth 2 are shown in structual relationship.
  • Figure 4 shows a lateral cross-section through a portion of the assembly with a side seam heat-seal 4 of the two layers of filter cloth, felt-to-felt, about the frame side member 5 and the undulating thermoplastic polymeric screen 3 bonded along each apex to the felt sides of 7 the filter cloths.
  • Side member 5. may be solid or entriely absent in some cases, in which case the two layer of filter cloth would be sealed together around the end or edge of section of the screen 3.
  • Heat-sealing, felt-to-felt or felt-to-screen, is the preferred way of forming the filter cloth assembly of this invention, but hot-melt adhesive bonding or other adhesives or glues could be used.
  • the heat for instance, could be supplied by laser, ultrasonically, by hot air, infrared radiation, or by other means known in the art. It is necessary to form bonds adequately strong to hold the materials of the filter cloth and screen together under the conditions of temperature, pressure corrosion, and the static and dynamic weight loads present in the filtrations being performed by the assembly of the invention.
  • Reasonable strength is also needed if the filter cake is to be dislodged from the filter surface with aid of back pressure or reverse pressure bumping, or other back pressure methods often utilized for this purpose.
  • the microporous organic polymeric membrane is perferably made from a porous from of polytetrafluoroethylene (PTFE), the most preferred materials being the expanded microporous forms (ePTFE) of PTFE disclosed in U.S. patents 4,187,390; 4,110,392; 4,096,227; 4,025,679; 3,962,153; and 3,953,566.
  • PTFE polytetrafluoroethylene
  • Other porous PTFE filter materials prepared by different processes, and other porous polymer membrane ⁇ materials, but known in the art to be useful as filter materials, and in laminates, and assemblies thereof may also be used.
  • microporus membranes formed from other organic polymers would also be functional, such as a microporous polypropylene membrane. Also applicable would be more conventional filter media.
  • the organic polymeric textile felt, bonded or laminated to the microporous membrane to form the filter cloth, is preferably polypropylene.
  • Other textile felts known in the filtration art to be useful for such composite filter cloths may also be used, such as a felt of polyester fiber, glass fiber, PTFE fiber, or others.
  • a unitary thermoplastic filter material may be used.
  • thermoplastic organic screen material which is formed into an undulating configuration, such as a regular sine wave configuration, or intop an angled (Fig. 5) or flattened angled (Fig.6) configuration, is placed between two sheets of the filter cloth adjacent the screen, and heat-bonded to each apex by the same methods as described above.
  • the unitary assembly so formed has considerable compression strength which is what is needed to prevent collapse under pressure filtration conditions.
  • the assembly has tested to support about 1 atm. compression, but is normally used at about 5 to 15 pounds per square inch.
  • the bonding prevents expansion or bagginess of the filter cloths during the cleaning cycle when the pressure is reversed and comes from within the filter assembly.
  • thermoplastic screening of about one half inch square opening screen size and made from, for example polypropylene, is appropriate for this application, is easily warned and bent over a mold to the desired undulating sine wave or angled configuration, cooled, heat-bonded to the felt sides of two filter fabric composites, formed around a frame, edges trimmed and heat-sealed around the frame or the edges of the unitary assembly, and the assembly closed and sealed at the top.
  • Other screen aperture sizes may be used a appropriate for strength or other reasons.
  • Other thermoplastic polymers and glass-fiber reinforced plastic screen materials may also be used. Glass fiber screening and metal screening materials may also be used in some cases in conjunction with supplemental thermoplastic material or adhesives to aid in bonding the filter membrane to the screening material .
  • the filter assembly frame may be of metal pipe or tubing or bent metal shapes formed so as to not puncture the filter cloth easily under pressure or usual movement necessary to use of the filter assembly.
  • the exact form is not critical to the invention and the pipe, metal shape, and wood header or manifold top bar which presently make up the frame being used in the art can be used in one of the embodiments of the present invention.
  • This invention in effect replaces the canvas filter cloth sewn into pockets and containing plastic shapes to hold the sides apart now supported on the above frame.
  • the metal frame of the assembly may be substituted by suitable plastic pipes and molded shapes of appropriate compostion and strength.
  • the header or manifold may take the form of molded plastic header or the form of a potted plastic manifold wherein the ends of the filter cloths, screen, and side bars are potted in a plastic form designated and formed to hold them and also a means for removing the liquid filtered through the filter cloths of the assembly. Methods well known in the art for potting ends of filters in plastic or metal forms can be utilized for this. It will be apparent to those skilled in the art that various modifications and changes in methods and materials could be made for making and using this invention without departing from the scope or spirit of the invention.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtering Materials (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

Ensemble intégré de panneaux filtrants se composant de tissus filtrante de polymère microporeux (2) que l'on a fixés par soudure aux pointes supérieures d'un tamis ondulé (3) de manière à former une unité filtrante solide qui soit résistante de manière uniforme à la pression, pour remplacer de fait les ensembles à panneaux filtrants. Le tamis ainsi que les côtés feutres des tissus filtrants sont de préférence fabriqués en une matière thermoplastique que l'on peut sceller à chaud, telle que le polypropylène habituel, de manière à pouvoir souder et sceller à chaud l'ensemble des coutures pour produire un ensemble unitaire résistant à la compression. La couche filtrante externe est, elle, de préférence en un polytétrafluoréthylène poreux expansé. On peut éventuellement monter dans l'ensemble filtre un cadre porteur rigide circonférentiel (5).
PCT/US1988/004038 1988-11-10 1988-11-10 Ensemble filtre a support integre WO1990005035A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1988/004038 WO1990005035A1 (fr) 1988-11-10 1988-11-10 Ensemble filtre a support integre

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1988/004038 WO1990005035A1 (fr) 1988-11-10 1988-11-10 Ensemble filtre a support integre

Publications (1)

Publication Number Publication Date
WO1990005035A1 true WO1990005035A1 (fr) 1990-05-17

Family

ID=22208993

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1988/004038 WO1990005035A1 (fr) 1988-11-10 1988-11-10 Ensemble filtre a support integre

Country Status (1)

Country Link
WO (1) WO1990005035A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006032736A1 (fr) * 2004-09-23 2006-03-30 Guy Gaudfrin Element filtrant pour liquides et installation de filtration comprenant un tel element
US7837756B2 (en) 2007-04-05 2010-11-23 Aaf-Mcquay Inc. Filter with ePTFE and method of forming

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1135458A (fr) * 1955-08-12 1957-04-29 Perfectionnement aux filtres à masse cellulosique filtrante
DE1065379B (de) * 1959-09-17 Dorr-Oliver Incorporated, Stamford, Conn. (V. St. A.) Filterelement
US3482702A (en) * 1967-11-22 1969-12-09 Dorr Oliver Inc Filter with media supporting grid structure
US3486627A (en) * 1967-02-21 1969-12-30 Carborundum Co Filter leaves

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1065379B (de) * 1959-09-17 Dorr-Oliver Incorporated, Stamford, Conn. (V. St. A.) Filterelement
FR1135458A (fr) * 1955-08-12 1957-04-29 Perfectionnement aux filtres à masse cellulosique filtrante
US3486627A (en) * 1967-02-21 1969-12-30 Carborundum Co Filter leaves
US3482702A (en) * 1967-11-22 1969-12-09 Dorr Oliver Inc Filter with media supporting grid structure

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006032736A1 (fr) * 2004-09-23 2006-03-30 Guy Gaudfrin Element filtrant pour liquides et installation de filtration comprenant un tel element
US7754078B2 (en) 2004-09-23 2010-07-13 Guy Gaudfrin Filtering element for liquids filtering installation comprising same
CN101027110B (zh) * 2004-09-23 2012-01-18 居伊·戈德弗兰 用于液体的过滤元件和包含该过滤元件的过滤装置
US7837756B2 (en) 2007-04-05 2010-11-23 Aaf-Mcquay Inc. Filter with ePTFE and method of forming
US8152889B2 (en) 2007-04-05 2012-04-10 Aaf-Mcquay Inc. Filter with EPTFE and method of forming

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